In recent years, the increased volume of air traffic in most airports has required airport ground personnel to more efficiently handle the increased traffic. One common ground activity which occurs at every airport is the movement of parked aircraft to different locations around the airport airfield by ground vehicles. For example, once an aircraft has landed and is parked, the aircraft may later need to be moved to another location. In this circumstance, ground equipment is used to move the aircraft in lieu of the aircraft moving under its own power. One critical step in the movement of aircraft by ground vehicles is the connection of the ground vehicle to the aircraft. A number of prior art devices exist which are intended to be used to couple a ground vehicle to an aircraft such as by a tow bar assembly.
U.S. Pat. No. 4,426,098 and U.S. Pat. No. 5,078,418 to Kalmanson each disclose a towing head characterized by a connecting structure including a rotatable cam that is selectively positionable into a locked or unlocked position by camming engagement of the rotatable cam with the tow pin of the aircraft. The rotation of the cam to the locked position causes the tow pin of the aircraft to be securely clamped between the connecting structure that may take the form of one or more hook members.
U.S. Pat. No. 4,418,936 to Adams, et al. discloses a tow bar coupling head which may be attached to the tow pin of an aircraft. The structure of this device includes a solid metal body portion with a transverse slot formed on its underside and within which the tow pin of the aircraft is received. A dead bolt slide lock retains the aircraft pin in place within the slot. A removable locking pin extending vertically through the body portion prevents accidental withdrawal of the dead bolt slide lock by use of a spring member to bias the slide lock in a closed position.
German Patent No. 3,705,740A1 discloses a tow bar assembly for connection to an aircraft in order to tow the same. The structure of this device incorporates two outer plates and a third plate positioned between the outer two plates. A sheer pin connects the two outer plates and is located in a cylindrical sleeve through the third plate. A rotatable handle member pivotally connected to the main body portion of the tow bar assembly is used to positively engage the tow pin of the aircraft.
The foregoing inventions are suitable for their intended purposes. However, each of the foregoing references require undue manual intervention in creating an initial connection between the aircraft and the tow bar assembly. This manual intervention first requires a holding step in that the tow bar assembly must first be held in alignment with the tow pin on the wheel assembly of the aircraft, and then requires a separate locking step to positively connect the tow bar assembly to the tow pin. For example, in the Kalmanson references, the tow bar assembly must first be held in alignment with the tow pin and then, while the tow bar assembly is held in a steady aligned position, the lever-type cam handle must be rotated in the desired direction in order to positively engage the towing head assembly with the tow pin. In both Adams, et al., and the German patent, two separate steps are required in the initial connection by first aligning the tow bar assembly and then rotating or pushing the handle member in a desired direction. Because of the weight and bulk of many tow bar assemblies, the mere manipulation of a handle while having to simultaneously hold the tow bar assembly in the aligned position can make it difficult to achieve a quick and secure connection.
In addition to the above-mentioned shortcomings, many of the prior art devices are structurally complex, difficult to maintain, and may be expensive to purchase.